Blender Git Loki

Unified the main Eigen solver function a bit for constrained/unconstrained
solver variants.

Ported the remaining implicit solver functions for Eigen.

Also added a couple of utility wrapper functions for Eigen types to make
interfacing with plain float arrays and blenlib math easier.

Updating Eigen implicit dynamics solver implementation to adhere to the
new mass-spring solver API.

Merge branch 'hair_immediate_fixes' into gooseberry

Compatibility fix for shape keys.

Avoid moving the 'from' pointer around in DNA. This way files stay back-
as well as forward-compatible. Only the additional type enum and
sub-index is stored in a new from_extra struct in shape keys now.

Fix for invalid ID access during versioning.

For now is fixed by doing a versioning hack in the lib_link function,
but would be nicer to avoid this altogether for forward compatibility.

Merge branch 'hair_immediate_fixes' into gooseberry

Merge branch 'master' into hair_immediate_fixes

Interpolation for non-simulated hairs in preview.

This generates a somewhat believable overall look for the hair system
by blending simulated hairs. For small number of hairs and small
preview ratios this can get quite inaccurate, but that's the tradeoff
for getting preview functionality ...

Calculate blending weights for preview hairs by constructing a kd-tree
of simulated hairs and using nearest neighbors.

Removed debug prints.

Solved various update issues with the hair preview factor.

This is still terribly messy, especially because every change of the
particle system has to be piped through the dummy cloth modifier somehow.
The automatic caching system also tends to get in the way a lot; after
changing the preview factor one basically always has to start at frame 1
currently because the cloth modifier has to be reconstructed and forgets
about all caching.

Widgets:

* Add option for shaded/non shaded widgets
* Normalize arrow widget size to 1.0 so size is predictable. Probably
will use the same scheme for other widgets as well

All translation axis now drawn and operated through the widget system.

* Manipulator Y 3D arrow moved and rotated correctly.
* Light manipulator doing undo now
* Scons should be fixed.

Green widget handles y translation properly.

ManipulatorGroup customdata.

Make WidgetGroup data private.

WidgetGroup now handles updating the manipulator properties.

Still not hooked new arrow widget to the system

Add python exporter that exports a mesh in a C file in a renderer-ready
format (vertices + normals + triangle vertex indices)

This will allow us to create widgets in blender instead of defining them
programmatically.

May also support facegroups for different colors in the future though
they must be somehow tied to the UI colors.

Enable depth testing for widgets.

Especially if we have many widgets on screen, sorting them will be
difficult and for mesh-armature widgets it will be unavoidable if we
want to avoid tweaking "back" surfaces.